Explorer 01

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General

Designation	00004 / 58001A
Launch date	1 Feb 1958
Country of origin	United States
Mission	Scientific: ionosphere study
Perigee/Apogee	347/1859 km
Inclination	33.2°
Period	107.2 min
Launch vehicle	Jupiter C (Juno 1 from the US Army, 18 t, 21 m tall, 4 stages)
Launch site	Cape Canaveral
Mass at launch	14.6 kg

Rocked realized by Wernher von Braun's team, a german engineer from Peenemünde. He had been working since 1953 at the Redstone Arsenal (Huntsville, Alabama) to design a balistic missile with the help of the Army Ballistic Missile Agency and the Jet Propulsion Laboratory.

First American satellite: height 1.2 m, diameter 20 cm. It was in fact the 4th stage of the rocket. Carrying 5 kg of instruments (batteries, radio transmitter, Geiger counter).

Has discovered Van Allen belts (radiations belts around the Earth) because the orbit was more excentric than expected.

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End of life

Out of service	23 May 1958
Decay	31 Mar 1970 in Southern Pacific

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